Among 12 GEP-NETs, eight showed mutations of more than one cancer-related gene, including TP53, CNBD1, RB1, APC, BCOR, BRAF, CTNNB1, EGFR, EP300, ERBB3, KDM6A, KRAS, MGA, MLL3, PTEN, RASA1, SMARCB1, SPEN, TBC1D12, and VHL. TP53 was recurrently mutated in three cases, whereas CNBD1 and RB1 mutations were identified in two cases. This evidence concerns the gene CTNNB1 and cancer.